Power supply circuit, power supply device and control method

ABSTRACT

Provided are a power supply circuit, a power supply device and a control method. The power supply circuit includes a primary rectifier unit, a modulation unit, a transformer, a secondary rectifier and filtering unit, a current feedback unit, an isolation unit and a control unit. The power supply circuit removes a liquid electrolytic capacitor at a primary side. In the power supply circuit, the liquid electrolytic capacitor at the primary side is removed, such that a volume of the power supply circuit is smaller, and is safe to use. Moreover, the control unit may determine a type of a voltage of input alternating current, and set a current limit value in the current feedback unit according to the type of the voltage of the alternating current.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2017/103007, filed Sep. 22, 2017, the entire disclosure of whichis incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to a charging technology field,and more particularly, to a power supply circuit, a power supply deviceand a control method.

BACKGROUND

A power supply circuit typically includes a primary conversion unit anda secondary conversion unit. The primary conversion unit generallyincludes a primary rectifier unit and a primary filtering unit. Theprimary filtering unit typically adopts one or more high-capacity liquidelectrolytic capacitors (such as, liquid aluminum electrolyticcapacitors) to perform primary filtering on a voltage after primaryrectification.

The liquid electrolytic capacitor has disadvantages of short life andeasy cracking, resulting in a short life and insecurity of aconventional power supply circuit.

SUMMARY

The present disclosure provides a power supply circuit, a power supplydevice and a control method.

In a first aspect, a power supply circuit is provided. The power supplycircuit includes: a primary rectifier unit, configured to performrectification on input alternating current to output a first voltagehaving a periodically changing voltage value; a modulation unit,configured to modulate the first voltage to generate a second voltage; atransformer, configured to generate a third voltage based on the secondvoltage; a secondary rectifier and filtering unit, configured to performrectification and filtering on the third voltage to generate an outputcurrent of the power supply circuit; a current feedback unit; anisolation unit; and a control unit. The current feedback unit isconfigured to receive the output current, and to send a feedback signalto the isolation unit when a current value of the output current reachesa preset current limit value. The isolation unit is configured totransmit the feedback signal to the modulation unit in an optoelectroniccoupling manner. The modulation unit is configured to perform modulatingthe first voltage to generate the second voltage according to thefeedback signal, to limit the current value of the output current belowthe current limit value. The control unit is configured to determine avoltage of the alternating current, to set the current limit value ofthe current feedback unit as a first current value when the voltage ofthe alternating current is of a first type, and to set the current limitvalue of the current feedback unit as a second current value when thevoltage of the alternating current is of a second type, in which anamplitude of the voltage of the first type is greater than that of thevoltage of the second type, and the first current value is greater thanthe second current value.

In a second aspect, a power supply device is provided. The power supplydevice includes a housing, a circuit board, and a power supply circuit.The circuit board is enclosed by the housing. The power supply circuitis positioned on the circuit board, and the power supply circuit is asdescribed in the first aspect.

In a third aspect, a control method of a power supply circuit isprovided. The control method includes: performing rectification on inputalternating current to output a first voltage having a periodicallychanging voltage value; modulating the first voltage to generate asecond voltage; generating a third voltage based on the second voltage;performing rectification and filtering on the third voltage to generatean output current of the power supply circuit; generating a feedbacksignal when a current value of the output current reaches a presetcurrent limit value; transmitting the feedback signal in anoptoelectronic coupling manner, such that modulating the first voltageto generate the second voltage is performed according to the feedbacksignal, to limit the current value of the output current below thecurrent limit value: determining a voltage of the alternating current;setting the current limit value as a first current value when thevoltage of the alternating current is of a first type; setting thecurrent limit value as a second current value when the voltage of thealternating current is of a second type, in which an amplitude of thevoltage of the first type is greater than that of the voltage of thesecond type, and the first current value is greater than the secondcurrent value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a power supply circuit according to anembodiment of the present disclosure.

FIG. 2 is a schematic diagram illustrating a waveform of a first voltageto be modulated according to an embodiment of the present disclosure.

FIG. 3 is a schematic diagram comparing voltage waveforms before andafter modulation of a conventional power supply circuit.

FIG. 4 is a schematic diagram illustrating a waveform of a secondvoltage obtained after modulating a first voltage according to anembodiment of the present disclosure.

FIG. 5 is a schematic diagram of a power supply circuit according toanother embodiment of the present disclosure.

FIG. 6 is a schematic diagram of a power supply circuit according to yetanother embodiment of the present disclosure.

FIG. 7 is a schematic diagram of a power supply circuit according tostill another embodiment of the present disclosure.

FIG. 8 is a schematic diagram illustrating a fast charging processaccording to an embodiment of the present disclosure.

FIG. 9 is a block diagram of a power supply device according to anembodiment of the present disclosure.

FIG. 10 is a schematic flow chart of a control method according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

In the related art, both a primary rectifier unit and a primaryfiltering unit are provided at a primary side of a power supply circuit.The primary filtering unit generally includes one or more liquidelectrolytic capacitors. The liquid electrolytic capacitor hasproperties of large capacity and strong filtering ability. Due to theexistence of the liquid electrolytic capacitor, an output provided bythe power supply circuit may be a constant direct current. However, theliquid electrolytic capacitor has disadvantages of short life and easycracking, resulting in a short life and insecurity of the power supplycircuit. Moreover, charging a battery in a device to be charged with theconstant direct current will result in polarization and lithiumprecipitation of the battery, such that a service life of the batterymay be reduced.

In order to improve the service life and safety of the power supplycircuit, and to relieve the polarization and lithium precipitation ofthe battery during charging process, embodiments of the presentdisclosure provide a power supply circuit without the liquidelectrolytic capacitor at the primary side. Such a power supply circuitmay be used to charge the battery in the device to be charged.

The device to be charged used in embodiments of the present disclosuremay refer to a mobile terminal, such as a “communication terminal” (or“terminal” for short). The “terminal” may include, but is not limited toa device configured to receive/transmit communication signals via awired connection (for example, public switched telephone network (PSTN),digital subscriber line (DSL) connection, digital cable connection,direct cable connection and/or another data connection/network) and/orvia a wireless interface (for example, cellular network, wireless localarea network (WLAN), digital TV network such as digital videobroadcasting handheld (DVB-H) network, satellite network, an amplitudemodulation-frequency modulation (AM-FM) broadcasting transmitter, and/ora wireless interface of another communication terminal). Thecommunication terminal configured to communicate via the wirelessinterface may be referred to as “wireless communication terminal”,“wireless terminal” and/or “mobile terminal”. Examples of a mobileterminal include, but are not limited to a satellite phone or a cellphone, a terminal combining a cell radio phone and a personalcommunication system (PCS) having capability of data process, fax, anddata communication, a personal digital assistant (PDA) including a radiophone, a pager, Internet/Intranet access, a web browser, a note pad &address book, a calendar and/or a global positioning system (GPS)receiver, and a common laptop and/or handheld receiver, or otherelectronic devices including a radio phone transceiver.

As illustrated in FIG. 1, the power supply circuit 1 according to anembodiment of the present disclosure may include a primary rectifierunit 11, a modulation unit 12, a transformer 13, a secondary rectifierand filtering unit 14, a current feedback unit 15 and an isolation unit17. In the following, respective components of the power supply circuit10 will be described in detail respectively.

The primary rectifier unit 11 may be configured to perform rectificationon input alternating current to output a first voltage having aperiodically changing voltage value. In some cases, the inputalternating current (AC) may be referred to as mains supply. The inputalternating current may be 220V alternating current, or may be 110Valternating current, which is not limited in embodiments of the presentdisclosure.

A voltage waveform of the first voltage is periodically changing. Asillustrated in FIG. 2, the waveform of the first voltage may be apulsating waveform or a steamed bun waveform.

Implementation of the primary rectifier unit 11 is not limited inembodiments of the present disclosure. The primary rectifier unit 11 maybe a full-bridge rectifier circuit formed of four diodes, or may be arectifier circuit in other forms, such as a half-bridge rectifiercircuit.

The modulation unit 12 may be configured to modulate the first voltageto generate a second voltage. In some cases, the modulation unit 12 maybe referred to as a chopper unit or a chopper. In other cases, themodulation unit 12 may be referred to as a clipper unit or a clipper. Inembodiments of the present disclosure, implementation of the modulationunit 12 is not limited. As an example, the modulation unit 12 may modulethe first voltage in a PWM (Pulse Width Modulation) mode, or maymodulate the first voltage in a frequency modulation mode.

It should be noted that, in the related art, a voltage output from theprimary rectifier unit 11 (corresponding to the first voltage inembodiments of the present disclosure) needs to be filtered by theprimary filtering unit (including one or more liquid electrolyticcapacitors) to form the constant direct current. A voltage waveform ofthe constant direct current is typically a straight line, i.e., thevoltage waveform before modulation as illustrated in FIG. 3. Then, themodulation unit modulates the constant voltage (chops the waveform), toform the voltage after modulation as illustrated in FIG. 3. It can beseen from FIG. 3 that, with the processing of the modulation unit, theconstant voltage signal is chopped into many small square wave pulsesignals with same amplitude.

In contrast, the power supply circuit provided by embodiments of thepresent disclosure removes the liquid electrolytic capacitor for primaryfiltering, and directly modulates the first voltage having theperiodically changing voltage value after the primary rectification.Taking the waveform of the first voltage illustrated in FIG. 2 as anexample, the waveform of the second voltage obtained after themodulation may be as illustrated in FIG. 4. It can be seen from FIG. 4that, the second voltage also contains may small pulse signals, however,amplitudes of these pulse signals are not identical and changeperiodically. The dashed line in FIG. 4 indicates an envelope of pulsesignals forming the second voltage. Compared with FIG. 2, the envelopeof pulse signals forming the second voltage is substantially same as thewaveform of the first voltage.

The transformer 13 may be configured to generate a third voltage basedon the second voltage. In other words, the transformer 13 may beconfigured to couple the second voltage from the primary side of thetransformer 13 to the secondary side of the transformer 13, to obtainthe third voltage. For example, the transformer 13 may be configured toperform voltage transformation related operation on the second voltageto obtain the third voltage. The transformer 13 may be a commontransformer, or may be a high-frequency transformer of which a workingfrequency ranges from 50 KHz to 2 MHz. The transformer 13 may include aprimary winding and a secondary winding. Forms of the primary windingand the secondary winding, and connection modes between the primarywinding and secondary winding and other units in the power supplycircuit 10 are related to types of a switching power supply used by thepower supply circuit. For example, the power supply circuit 10 may bebased on a flyback switching power supply, a forward switching powersupply, or a push-pull switching power supply. With different types ofthe switching power supply on which the power supply circuit is based,the specific forms and the connection modes of the primary winding andthe secondary winding of the transformer may be different, which is notlimited in embodiments of the present disclosure. FIG. 1 merelyillustrates one possible connection mode of the transformer 13.

The secondary rectifier and filtering unit 14 may include a secondaryrectifier unit and a secondary filtering unit. The filtering mode of thesecondary filtering unit is not limited in embodiments of the presentdisclosure. As an example, the secondary filtering unit 14 may adopt aSR (synchronous rectifier) chip to perform synchronous rectification onthe voltage (or current) induced by the secondary winding of thetransformer. As another example, the secondary filtering unit may adopta diode to perform secondary rectification. The secondary filtering unitmay be configured to perform secondary filtering on the voltage afterthe secondary rectification. The secondary filtering unit may includeone or more solid capacitors, or may include a combination of solidcapacitors and common capacitors (such as, ceramic capacitors).

It can be seen from the above description that, in the power supplycircuit 10 provided by embodiments of the present disclosure, the liquidelectrolytic capacitor at the primary side is removed, such that thevolume of the power supply circuit is reduced, and the service life andsafety of the power supply circuit is improved.

The current feedback unit 15 may be configured to receive the outputcurrent of the power supply circuit 10, and to send a feedback signal tothe isolation unit 17 (for example, an optoelectronic coupler) when acurrent value of the output current reaches a preset current limitvalue.

The isolation unit 17 may be configured to transmit the feedback signalto the modulation unit 12 in an optoelectronic coupling manner. Theisolation unit 17 may be located between the current feedback unit 15and the modulation unit 12. The isolation unit 17 may be configured toisolate the primary side and the secondary side of the power supplycircuit 10 from each other, to prevent mutual interference of signals atthe primary side and the secondary side. The isolation unit 17, forexample, may be an optical coupling unit, or may be of other types,which is not limited in embodiments of the present disclosure.

The modulation unit 12 may be configured to perform the procedure ofmodulating the first voltage to generate the second voltage according tothe feedback signal, to limit the current value of the output currentbelow the current limit value.

Taking the modulation unit 12 being based on a PWM controller as anexample, the procedure of the modulation unit 12 modulating the firstvoltage to generate the second voltage is illustrated as follows. Whenthe power supply circuit 10 just starts working, the output current ofthe power supply circuit 10 is relatively small. In this case, themodulation unit 12 may module the first voltage by continuouslyincreasing a duty ratio of a PWM control signal, to generate the secondvoltage, such that the power supply circuit 10 may draw more energy fromthe input alternating current in unit time, thus continuously increasingthe output current of the power supply circuit 10. When the outputcurrent of the power supply circuit 10 reaches the current limit valueof the current feedback unit 15, the modulation unit 12 receives thefeedback signal sent by the current feedback unit 15. In this case, themodulation unit 12 may modulate the first voltage by controlling theduty ratio of the PWM control signal to keep unchanged, to generate thesecond voltage, such that the output current of the power supply circuit10 does not exceed the current limit value.

As an example, the current feedback unit 15 may include a currentsampling unit and an operational amplifier. The current sampling unitmay be configured to sample the output current of the power supplycircuit 10, and to transmit the sampling voltage corresponding to theoutput current of the power supply circuit 10 to a negative input end ofthe operational amplifier. A voltage at a positive end of the currentfeedback unit 15 is a reference voltage. A voltage value of thereference voltage decides the current limit value of the currentfeedback unit 15. Therefore, the current limit value of the currentfeedback unit 15 may be adjusted by adjusting the voltage at thepositive end of the current feedback unit 15.

The current feedback unit 15 may be directly coupled to the modulationunit 12, or may be indirectly coupled to the modulation unit 12 via anoptocoupler, which is not limited in embodiments of the presentdisclosure. When the current feedback unit 15 is directly coupled to themodulation unit 12 via the optocoupler, the feedback signal sent by thecurrent feedback unit 15 to the modulation unit needs to be firstoptic-electric converted by the optocoupler.

The power supply circuit 10 provided by embodiments of the presentdisclosure removes the liquid electrolytic capacitor at the primaryside, and the capacitor (such as solid capacitor) in the secondaryrectifier and filtering unit 14 has a weak ability in outputting directcurrent, and thus it is easy to occur overload (when the overloadoccurs, the output current of the power supply circuit 10 increasessignificantly). Therefore, there is a need to monitor the output currentof the power supply circuit 10 in real time by using the currentfeedback unit 15, to limit the current value of the output current belowthe set current limit value all the time, avoiding the overload.

The input alternating current (mains supply) received by the firstrectifier unit may be of different voltage types, for example, may be220V alternating current, or may be 110V alternating current. The higherthe voltage of the alternating current is, the more energy the powersupply circuit can draw from the alternating current in unit time, andaccordingly, the higher the direct current capability of the powersupply circuit 10 is. Therefore, during charging the device to becharged with the constant direct current, the power supply circuit 10may set corresponding current limit value for the current feedback unit15 according to the voltage type of the alternating current. In detail,the power supply circuit may further include a control unit 16. Thecontrol unit 16 may be an MCU (micro-control unit). The control unit maycontrol other units in the power supply circuit 10 by sending controlsignals to the other units in the power supply circuit 10. The controlunit 16 may be configured to determine the voltage of the alternatingcurrent. when the voltage of the alternating current is of a first type,the control unit 16 may set the current limit value of the currentfeedback unit 15 as a first current value. When the voltage of thealternating current is of a second type, the control unit 16 may set thecurrent limit value of the current feedback unit 15 as a second currentvalue. An amplitude (or valid value) of the voltage of the first type isgreater than that of the voltage of the second type, and the firstcurrent value is greater than the second current value. In other words,the higher the amplitude (or valid value) of the voltage of thealternating current is, the stronger the direct current capability ofthe power supply circuit 10 is, and in this case, a higher current limitvalue is set by the control unit 16 for the current feedback unit 15 inembodiments of the present disclosure, such that the power supplycircuit 10 may work in a wider current range. The lower the amplitude(or valid value) of the voltage of the alternating current is, theweaker the direct current capability of the power supply circuit 10 is,and in this case, a lower current limit value is set by the control unit16 for the current feedback unit 15 in embodiments of the presentdisclosure, such that safety of the charging process is ensured.

The control unit 16 may adjust the current limit value of the currentfeedback unit 15 in various ways. for example, the control unit 16 maybe coupled to a positive input end of the operational amplifier in thecurrent feedback unit 15 and the control unit 16 may adjust the currentlimit value of the current feedback unit 15 by adjusting the referencevoltage received by the positive input end.

It should be understood that, the first current value and the secondcurrent value may be calculated according to the direct current outputcapability reachable by the power supply circuit 10 under the first typeof alternating current and the second type of alternating current. Forexample, after system design is completed, the direct current outputcapability reachable by the power supply circuit 10 under the first typeof alternating current and the second type of alternating current may bemeasured, thus calculating the first current value and the secondcurrent value.

In embodiments of the present disclosure, the way in which the controlunit 16 determines the voltage type of the alternating current is notlimited. For example, the type (or size) of the alternating current maybe determined according to the first voltage outputted by the primaryrectifier unit 11, or the type (or size) of the alternating current maybe determined according to the third voltage received by the secondaryrectifier and filtering unit 14. The ways for determining the voltagetype of the alternating current will be illustrated in detail below withspecific embodiments.

In some embodiments, as illustrated in FIG. 5, the power supply circuit10 may further include a first rectifier unit 51, a first filtering unit52 and a voltage signal conversion unit 53. The first rectifier unit 51may be configured to receive the third voltage, and to performrectification on the third voltage to obtain a fourth voltage. The firstfiltering unit 52 may be configured to receive the fourth voltage, andto perform filtering on the fourth voltage to obtain a fifth voltage.The voltage signal conversion unit 53 may be configured to convert thefifth voltage to an indication signal for indicating the voltage type ofthe alternating current. The control unit 16 may be configured toreceive the indication signal, and to determine the voltage type of thealternating current according to the indication signal.

It should be understood that, after the rectification of the firstrectifier unit and the filtering of the first filtering unit 52, thevoltage value of the fifth voltage is in positive proportion to thevalid value (220V or 110V) or the amplitude of the input alternatingcurrent. In some embodiments, the fifth voltage may also be referred toas a forward voltage. In embodiments of the present disclosure, thevoltage type of the alternating current may be determined by using thefifth voltage. Several specific determining ways are illustrated asfollows.

As an example, the voltage signal conversion unit 53 may be configuredto sample the fifth voltage. Accordingly, the indication signaloutputted by the voltage signal conversion unit 53 may be a samplingvoltage of the fifth voltage. Taking FIG. 6 as an example, the secondaryrectifier and filtering unit 14 may include a secondary synchronousrectification unit mainly consisting of a SR chip for synchronousrectification, a switch tube Q1 and a diode D1, and a secondaryfiltering unit mainly consisting of a capacitor C2. The first rectifierunit 51 may be implemented by the diode D2 in FIG. 6, and configured toperform rectification on the third voltage outputted by a secondarywinding of the transformer 13 to obtain the fourth voltage. The firstfiltering unit 52 may be implemented by the capacitor C1 in FIG. 6, andconfigured to perform filtering on the fourth voltage outputted by thediode D2 to obtain the fifth voltage. The voltage signal conversion unit53 may be implemented by the resistor R1 and the resistor R2 in FIG. 6,and configured to sample the voltage signal to obtain the samplingvoltage. The sampling voltage may be configured to represent a size ofthe fifth voltage. Since the fifth voltage is in positive proportion tothe valid value (or amplitude) of the voltage of the alternatingcurrent, the sampling voltage may be configured to represent the validvalue (or amplitude) of the voltage of the alternating current, and thusrepresent the voltage type of the alternating current. For example, thesampling voltage may be configured to represent whether the inputalternating current is 220V alternating current or 110V alternatingcurrent. The control unit 16 may be configured to receive the samplingvoltage, and to determine the voltage type of the alternating currentaccording to the sampling voltage. As illustrated in FIG. 6, the controlunit 16, for example, may be coupled to a node between the resistor R1and the resistor R2 via an ADC (analog-to-digital converter), to obtainthe sampling voltage.

As another example, the voltage signal conversion unit 53 may beconfigured to determine the voltage type of the alternating currentaccording to the fifth voltage, and to generate the indication signalaccording to the determined voltage type of the alternating current. Theindication signal is one of a high level and a low level. When theindication signal is the high level, the indication signal is configuredto indicate that the voltage of the alternating current is of the firsttype, and when the indication signal is the low level, the indicationsignal is configured to indicate that the voltage of the alternatingcurrent is of the second type. Or, when the indication signal is thehigh level, the indication signal is configured to indicate that thevoltage of the alternating current is of the second type, and when theindication signal is the low level, the indication signal is configuredto indicate that the voltage of the alternating current is of the firsttype.

In embodiments of the present disclosure, the high level or the lowlevel is generated according to the fifth voltage, to indicate thevoltage type of the alternating current, which may simplify thedetermining logic of the control unit 16.

One implementation in which the voltage signal conversion unit 53converts the fifth voltage to the high level or the low level isillustrated below with reference to FIG. 7.

As illustrated in FIG. 7, the voltage signal conversion unit 53 includesa voltage-stabilizing tube ZD and a triode s1. The voltage-stabilizingtube ZD may be configured such that, when the voltage of the alternatingcurrent is of the first type, both the voltage-stabilizing tube ZD andthe triode s1 are switched on, and a collector of the triode s1 is atthe low level, and when the voltage of the alternating current if of thesecond type, both the voltage-stabilizing tube ZD and the triode s1 areswitched off, and the collector of the triode s1 is at the high level.The control unit 16 may be coupled to the collector of the triode s1,and use the voltage signal at the collector as the indication signal forindicating the voltage type of the alternating current.

For example, when the input alternating current is 220V alternatingcurrent, the voltage dividing among the resistor R1, thevoltage-stabilizing tube ZD and the resistor R2 makes thevoltage-stabilizing tube ZD occur avalanche and switched on, a highervoltage is received at a gate of the triode s1, controlling the triodes1 to switch on. In this case, the voltage of the collector of thetriode s1 is the low level, indicating that the alternating current isthe 220V alternating current. when the input alternating current is 110Valternating current, the voltage dividing among the resistor R1, thevoltage-stabilizing tube ZD and the resistor R2 makes thevoltage-stabilizing tube ZD switched off, the voltage at the gate of thetriode s1 is the low level, controlling the triode s1 to switch off. Inthis case, the voltage of the collector of the triode s1 is the highlevel, indicating that the alternating current is the 110V alternatingcurrent.

It should be noted that, FIG. 7 merely illustrates an example ofimplementation of the voltage signal conversion unit 53. In practice,the functions of the voltage signal conversion unit 53 may beimplemented by other elements, such as a comparator.

In the related art, a power supply circuit for charging the device to becharged is proposed. This power supply circuit operates in a constantvoltage mode. In the constant voltage mode, the output voltage of thispower supply circuit keeps substantially constant, for example, 5V, 9V,12V or 20V.

The output voltage of the power supply circuit is not suitable for beingdirectly applied to both ends of the battery. Instead, the outputvoltage of the power supply circuit needs to be converted by aconversion circuit in the device to be charged, such that a chargingvoltage and/or a charging current expected by the battery in the deviceto be charged is obtained.

The conversion circuit is configured to convert the output voltage ofthe power supply circuit, to meet a requirement of the charging voltageand/or charging current expected by the battery.

As an example, the conversion circuit may be a charging managementmodule, such as a charging integrated circuit (IC). During a chargingprocess of the battery, the conversion circuit may be configured tomanage the charging voltage and/or charging current of the battery. Theconversion circuit may have at least one of a voltage feedback functionand a current feedback function, so as to manage the charging voltageand/or charging current of the battery.

For example, the charging process of the battery may include at leastone of a trickle charging stage, a constant current charging stage and aconstant voltage charging stage. In the trickle charging stage, theconversion circuit may utilize a current feedback loop to ensure that acurrent flowing into the battery in the trickle charging stage meets thecharging current (such as a first charging current) expected by thebattery. In the constant current charging stage, the conversion circuitmay utilize a current feedback loop to ensure that the current flowinginto the battery in the constant current charging stage meets thecharging current (such as a second charging current, which may begreater than the first charging current) expected by the battery. In theconstant voltage charging stage, the conversion circuit may utilize avoltage feedback loop to ensure that a voltage applied to both ends ofthe battery in the constant voltage charging stage meets the chargingvoltage expected by the battery.

As an example, when the output voltage of the power supply circuit isgreater than the charging voltage expected by the battery, theconversion circuit may be configured to perform a buck conversion on theoutput voltage of the power supply circuit to enable a buck-convertedcharging voltage to meet the requirement of the charging voltageexpected by the battery. As another example, when the output voltage ofthe power supply circuit is less than the charging voltage expected bythe battery, the conversion circuit may be configured to perform a boostconversion on the output voltage of the power supply circuit to enable aboost-converted charging voltage to meet the requirement of the chargingvoltage expected by the battery.

As another example, assume that the power supply circuit outputs aconstant voltage of 5V. When the battery includes a single battery cell(such as a lithium battery cell, a charging cut-off voltage of a singlebattery cell is typically 4.2V), the conversion circuit (for example, abuck circuit) may perform a buck conversion on the output voltage of thepower supply circuit, such that the charging voltage obtained after thebuck conversion meets a requirement of the charging voltage expected bythe battery.

As yet another example, assume that the power supply circuit outputs aconstant voltage of 5V. When the power supply circuit charges aplurality of (two or more) battery cells (such as lithium battery cell,a charging cut-off voltage of a single battery cell is typically 4.2V)coupled in series, the conversion circuit (for example, a boost circuit)may perform a boost conversion on the output voltage of the power supplycircuit, such that the charging voltage obtained after the boostconversion meets a requirement of the charging voltage expected by thebattery.

Limited by a poor conversion efficiency of the conversion circuit, apart of electric energy is lost in a form of heat, and the heat maygather inside the device to be charged. A design space and a space forheat dissipation of the device to be charged are small (for example, thephysical size of a mobile terminal used by a user becomes thinner andthinner, while plenty of electronic elements are densely arranged in themobile terminal to improve performance of the mobile terminal), whichnot only increases difficulty in designing the conversion circuit, butalso results in that it is hard to dissipate the heat gathered in thedevice to be charged, thus further causing an abnormity of the device tobe charged.

For example, the heat gathered on the conversion circuit may cause athermal interference on electronic elements neighboring the conversioncircuit, thus causing abnormal operations of the electronic elements;and/or for another example, the heat gathered on the conversion circuitmay shorten the service life of the conversion circuit and neighboringelectronic elements; and/or for yet another example, the heat gatheredon the conversion circuit may cause a thermal interference on thebattery, thus causing abnormal charging and/or abnormal discharging ofthe battery; and/or for still another example, the heat gathered on theconversion circuit may increase the temperature of the device to becharged, thus affecting user experience during the charging; and/or forstill yet another example, the heat gathered on the conversion circuitmay short-circuit the conversion circuit, such that the output voltageof the power supply circuit is directly applied to both ends of thebattery, thus causing abnormal charging of the battery, which bringssafety hazard if the over-voltage charging lasts for a long time, forexample, the battery may explode.

Embodiments of the present disclosure further provide a power supplycircuit 10. The control unit 16 in the power supply circuit 10 may beconfigured to communicate with the device to be charged, to adjust anoutput power of the power supply circuit 10, such that the outputvoltage and/or the output current of the power supply circuit 10 matchesa charging stage where the battery in the device to be charged iscurrently.

It should be understood that, the charging stage where the battery iscurrently may include at least one of a trickle charging stage, aconstant current charging stage and a constant voltage charging stage.

Taking the charging stage where the battery is currently being theconstant voltage charging stage as an example, communicating with thedevice to be charged, to adjust the output power of the power supplycircuit, such that the output voltage and/or the output current of thepower supply circuit matches the charging stage where the battery in thedevice to be charged is currently, includes: in the constant voltagecharging stage, communicating with the device to be charged, to adjustthe output power of the power supply circuit, such that the outputvoltage of the power supply circuit matches the charging voltagecorresponding to the constant voltage charging stage.

Taking the charging stage where the battery is currently being theconstant current charging stage as an example, communicating with thedevice to be charged, to adjust the output power of the power supplycircuit, such that the output voltage and/or the output current of thepower supply circuit matches the charging stage where the battery in thedevice to be charged is currently, includes: in the constant currentcharging stage, communicating with the device to be charged, to adjustthe output power of the power supply circuit, such that the outputcurrent of the power supply circuit matches the charging currentcorresponding to the constant current charging stage.

The power supply circuit 10 having communication function provided byembodiments of the present disclosure will be illustrated in detailbelow.

The power supply circuit 10 may obtain status information of thebattery. The status information of the battery may include presentelectric quantity information and/or voltage information of the battery.The power supply circuit 10 may adjust the output voltage of the powersupply circuit 10 itself according to be obtained status information ofthe battery, to meet the requirement of the charging voltage and/orcharging current expected by the battery. The voltage outputted by thepower supply circuit 10 after adjustment may be directly applied to bothends of the battery for charging the battery (hereinafter, referred toas “direct charging”). Further, during the constant current chargingstage of the process of charging the battery, the voltage outputted bythe power supply circuit 10 after adjustment may be directly applied toboth ends of the battery for charging the battery.

The power supply circuit 10 may have a voltage feedback function and acurrent feedback function, so as to manage the charging voltage and/orcharging current of the battery.

The power supply circuit 10 adjusting the output voltage of the powersupply circuit 10 itself according to the obtained status information ofthe battery may mean that, the power supply circuit 10 may obtain thestatus information of the battery in real time, and adjust the outputvoltage of the power supply circuit 10 itself according to the obtainedreal-time status information of the battery, to meet the chargingvoltage and/or charging current expected by the battery.

The power supply circuit 10 adjusting the output voltage of the powersupply circuit 10 itself according to the obtained real-time statusinformation of the battery may mean that, as the voltage of the batterycontinuously increases during the charging process, the power supplycircuit 10 may obtain the present status information of the battery atdifferent time points in the charging process, and adjust the outputvoltage of the power supply circuit 10 itself in real time according tothe present status information of the battery, to meet the requirementof the charging voltage and/or charging current expected by the battery.

For example, the charging process of the battery may include at leastone of a trickle charging stage, a constant current charging stage and aconstant voltage charging stage. In the trickle charging stage, thepower supply circuit 10 may output a first charging current in thetrickle charging stage to charge the battery, so as to meet therequirement of the charging current expected by the battery (the firstcharging current may be the constant direct current). In the constantcurrent charging stage, the power supply circuit 10 may utilize acurrent feedback loop to ensure that the current outputted by the powersupply circuit 10 and flowing into the battery in the constant currentcharging stage meets the requirement of the charging current expected bythe battery (such as a second charging current, which may also be acurrent with a pulsating waveform, and may be greater than the firstcharging current, which may mean that, a peak value of the current withthe pulsating waveform in the constant current charging stage is greaterthan that of the current with the pulsating waveform in the tricklecharging stage, while “constant current” of the constant currentcharging stage means that, in the constant current charging stage, apeak value or a mean value of the current with the pulsating waveform isbasically constant). In the constant voltage charging stage, the powersupply circuit 10 may utilize a voltage feedback loop to ensure that avoltage outputted from the power supply circuit 10 to the device to becharged in the constant voltage charging stage (i.e., the constantdirect voltage) keeps constant.

For example, the power supply circuit 10 mentioned in embodiments of thepresent disclosure may be mainly configured to control the constantcurrent charging stage of the battery in the device to be charged. Inother embodiments, controlling the trickle charging stage and theconstant voltage charging stage of the battery in the device to becharged may also be completed cooperatively by the power supply circuit10 and an additional charging chip in the device to be charged. Comparedto that in the constant current charging stage, the charging poweraccepted by the battery in the trickle charging stage and the constantvoltage charging stage is less, and the efficiency conversion loss andthe heat accumulation of the charging chip in the device to be chargedis acceptable.

It should be noted that, the constant current charging stage or theconstant current stage mentioned in embodiments of the presentdisclosure may refer to a charging mode in which the output current ofthe power supply circuit 10 is controlled, and does not require theoutput current of the power supply circuit 10 to keep completelyconstant and unchanged. For example, the constant current may refer tothat, a peak value or a mean value of the current with the pulsatingwaveform outputted by the power adapter is basically constant, or keepsconstant during a certain time period. For example, in practice, thepower supply circuit 10 typically performs charging by means ofmulti-stage constant current charging in the constant current chargingstage.

The multi-stage constant current charging may include N constant currentstages, where N is an integer no less than 2. The first charging stageof the multi-stage constant current charging starts with a predeterminedcharging current. N constant current stages in the multi-stage constantcurrent charging are performed in sequence from the first charging stageto the (N−1)th charging stage. After the constant current charging isswitched from one constant current stage to the next constant currentstage, the peak value of the current may be decreased. When the batteryvoltage reaches a charging stop voltage threshold, the constant currentcharging is switched from the present constant current stage to the nextconstant current stage. The current change between two adjacent constantcurrent stages may be gradual, or may be in a stepped skip manner.

Further, in a case where the output current of the power supply circuit10 is the current having the current value periodically changing (suchas the pulsating direct current), the constant current mode may refer toa charging mode in which the peak value or the mean value of the currentperiodically changing is controlled, i.e., the peak value of the outputcurrent of the power supply circuit 10 is controlled to not exceed thecurrent corresponding to the constant current mode. Moreover, in a casewhere the output current of the power supply circuit 10 is thealternating current, the constant current mode refers to a charging modein which the peak value of the alternating current is controlled.

In some embodiments, the power supply circuit 10 supports a firstcharging mode and a second charging mode, and a charging speed of thepower supply circuit 10 charging the battery in the second charging modeis greater than a charging mode of the power supply circuit 10 chargingthe battery in the first charging mode. In other words, compared to thepower supply circuit 10 working in the first charging mode, the powersupply circuit 10 working in the second charging mode may take a shortertime to fully charge the battery with a same capacity. Further, in someembodiments, in the first charging mode, the power supply circuit 10charges the battery via a second charging channel, and in the secondcharging mode, the power supply circuit 10 charges the battery via afirst charging channel.

The first charging mode may be a normal charging mode, and the secondcharging mode may be a fast charging mode. The normal charging mode mayrefer to a charging mode in which the power supply circuit 10 outputs arelatively smaller current value (typically less than 2.5A) or chargesthe battery in the device to be charged with a relatively smaller power(typically less than 15). In the normal charging mode, it typicallytakes several hours to fully fill a larger capacity battery (such as abattery with 3000 mAh). However, in the fast charging mode, the powersupply circuit 10 can output a relatively large current (typicallygreater than 2.5A, such as 4.5A, 5A or higher) or charges the battery inthe device to be charged with a relatively large power (typicallygreater than or equal to 15 W). Compared to the normal charging mode,the period of time may be significantly shortened when the battery withthe same capacity is fully filled by the power supply circuit 10 in thefast charging mode, and the charging is faster.

As indicated above, the output current of the power supply circuit 10may have the waveform with the current value periodically changing. Thewaveform may refer to the waveform of the output current of the powersupply circuit 10 working in the second charging mode. In the firstcharging mode, the voltage value of the output voltage of the powersupply circuit 10 is constant, and the waveform of the output currentvaries with the load.

Further, the device to be charged may perform bidirectionalcommunication with the power supply circuit 10 (or the control unit 16in the power supply circuit 10), to control the output of the powersupply circuit 10 in the second charging mode (i.e., control thecharging voltage and/or the charging current provided by the powersupply circuit 10 in the second charging mode). The device to be chargedmay include a charging interface, and the device to be charged maycommunicate with the power supply circuit 10 via a data wire of thecharging interface. Taking the charging interface being a USB interfaceas an example, the data wire may be a D+ wire and/or a D− wire of theUSB interface. Or, the device to be charged may perform wirelesscommunication with the power supply circuit 10.

The communicated content between the power supply circuit 10 and thedevice to be charged is not limited in embodiments of the presentdisclosure, and the control method of the device to be charged on theoutput of the power supply circuit 10 in the second charging mode isalso not limited in embodiments of the present disclosure. For example,the device to be charged may communicate with the power supply circuit10 to obtain the present voltage or present electric quantity of thebattery in the device to be charged, and adjust the output voltage oroutput current of the power supply circuit 10 based on the presentvoltage or present electric quantity of the battery. In the following,the communicated content between the power supply circuit 10 and thedevice to be charged and the control method of the device to be chargedon the output of the power supply circuit 10 in the second charging modewill be described in detail in combination with specific embodiments.

The master-slave relation of the power supply circuit 10 and the deviceto be charged is not limited in embodiments of the present disclosure.In other words, any of the power supply circuit 10 and the device to becharged can be configured as the master device for initiating thebidirectional communication session, accordingly, the other one can beconfigured as the slave device for making a first response or a firstreply to the communication initiated by the master device. As a feasibleimplementation, during the communication, the identities of the masterdevice and the slave device can be determined by comparing theelectrical levels of the power supply circuit 10 and the device to becharged relative to the ground.

The specific implementation of bidirectional communication between thepower supply circuit 10 and the device to be charged is not limited inembodiments of the present disclosure. In other words, any of the powersupply circuit 10 and the device to be charged can be configured as themaster device for initiating the communication session, accordingly, theother one can be configured as the slave device making a first responseor a first reply to the communication session initiated by the masterdevice, and the master device is able to make a second response to thefirst response or the first reply of the slave device, and thus anegotiation about a charging mode can be realized between the masterdevice and the slave device. As a feasible implementation, a chargingoperation between the master device and the slave device is performedafter a plurality of negotiations about the charging mode are completedbetween the master device and the slave device, such that the chargingprocess can be performed safely and reliably after the negotiation.

As an implementation, the mater device is able to make a second responseto the first response or the first reply made by the slave device to thecommunication session in a manner that, the master device is able toreceive the first response or the first reply made by the slave deviceto the communication session and to make a targeted second response tothe first response or the first reply. As an example, when the masterdevice receives the first response or the first reply made by the slavedevice to the communication session in a predetermined time period, themaster device makes the targeted second response to the first responseor the first reply of the slave device in a manner that, the masterdevice and the slave device complete one negotiation about the chargingmode, and a charging process may be performed between the master deviceand the salve device in the first charging mode or the second chargingmode, i.e., the power supply circuit 10 charges the device to be chargedin the first charging mode or the second charging mode according to anegotiation result.

As another implementation, the mater device is able to make a secondresponse to the first response or the first reply made by the slavedevice to the communication session in a manner that, when the masterdevice does not receive the first response or the first reply made bythe slave device to the communication session in the predetermined timeperiod, the mater device also makes the targeted second response to thefirst response or the first reply of the slave device. As an example,when the master device does not receive the first response or the firstreply made by the slave device to the communication session in thepredetermined time period, the mater device makes the targeted secondresponse to the first response or the first reply of the slave device ina manner that, the master device and the slave device complete onenegotiation about the charging mode, and the charging process isperformed between the mater device and the slave device in the firstcharging mode, i.e., the power supply circuit 10 charges the device tobe charged in the first charging mode.

In some embodiments, when the device to be charged is configured as themater device for initiating the communication session, after the powersupply circuit 10 configured as the slave device makes the firstresponse or the first reply to the communication session initiated bythe master device, it is unnecessary for the device to be charged tomake the targeted second response to the first response or the firstreply of the power supply circuit 10, i.e., one negotiation about thecharging mode is regarded as completed between the power supply circuit10 and the device to be charged, and the power supply circuit 10 is ableto charge the device to be charged in the first charging mode or thesecond charging mode according to the negotiation result.

In some embodiments, the device to be charged may perform bidirectionalcommunication with the power supply circuit 10 to control the output ofthe power supply circuit 14 in the second charging mode as follows. Thedevice to be charged performs the bidirectional communication with thepower supply circuit 10 to negotiate the charging mode between the powersupply circuit 10 and the device to be charged.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 tonegotiate the charging mode between the power supply circuit 10 and thedevice to be charged as follows. The device to be charged receives afirst instruction sent by the power supply circuit 10, in which thefirst instruction is configured to query the device to be chargedwhether to operate in the second charging mode. The device to be chargedsends a reply instruction of the first instruction to the power supplycircuit 10, in which the reply instruction of the first instruction isconfigured to indicate whether the device to be charged agrees tooperate in the second charging mode. When the device to be chargedagrees to operate in the second charging mode, the device to be chargedcontrols the power supply circuit 10 to charge the battery via the firstcharging channel.

In some embodiments, the device to be charged may perform bidirectionalcommunication with the power supply circuit 10 to control the output ofthe power supply circuit 14 in the second charging mode as follows. Thedevice to be charged performs the bidirectional communication with thepower supply circuit 10 to determine the charging voltage outputted bythe power supply circuit 10 in the second charging mode for charging thedevice to be charged.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 todetermine the charging voltage outputted by the power supply circuit 10in the second charging mode for charging the device to be charged asfollows. The device to be charged receives a second instruction sent bythe power supply circuit 10, in which the second instruction isconfigured to query whether the output voltage of the power supplycircuit 10 matches the present voltage of the battery in the device tobe charged. The device to be charged sends a reply instruction of thesecond instruction to the power supply circuit 10, in which the replyinstruction of the second instruction is configured to indicate that theoutput voltage of the power supply circuit 10 matches the presentvoltage of the battery, or is higher or lower than the present voltageof the battery. In some embodiments, the second instruction can beconfigured to query whether the present output voltage of the powersupply circuit 10 is suitable for being used as the charging voltageoutputted by the power supply circuit 10 in the second charging mode forcharging the device to be charged, and the reply instruction of thesecond instruction can be configured to indicate the present outputvoltage of the power supply circuit 10 is suitable, high or low.

When the present output voltage of the power supply circuit 10 matchesthe present voltage of the battery or the present output voltage of thepower supply circuit 10 is suitable for being used as the chargingvoltage outputted by the power supply circuit 10 in the second chargingmode for charging the device to be charged, it indicates that thepresent output voltage of the power supply circuit 10 may be slightlyhigher than the present voltage of the battery, and a difference betweenthe output voltage of the power supply circuit 10 and the presentvoltage of the battery is within a predetermined range (typically in anorder of hundreds of millivolts). When the present output voltage of thepower supply circuit 10 is higher than the present voltage of thebattery, it indicates that the difference between the output voltage ofthe power supply circuit 10 and the present voltage of the battery isabove the predetermined range. When the present output voltage of thepower supply circuit 10 is lower than the present voltage of thebattery, it indicates that the difference between the output voltage ofthe power supply circuit 10 and the present voltage of the battery isbelow the predetermined range.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 to controlthe output of the power supply circuit 10 in the second charging mode asfollows. The device to be charged may perform the bidirectionalcommunication with the power supply circuit 10 to determine the chargingcurrent outputted by the power supply circuit 10 in the second chargingmode for charging the device to be charged

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 todetermine the charging current outputted by the power supply circuit 10in the second charging mode for charging the device to be charged asfollows. The device to be charged receives a third instruction sent bythe power supply circuit 10, in which the third instruction isconfigured to query a maximum charging current presently supported bythe device to be charged. The device to be charged sends a replyinstruction of the third instruction to the power supply circuit 10, inwhich the reply instruction of the third instruction is configured toindicate the maximum charging current presently supported by the deviceto be charged. The power supply circuit 10 determines the chargingcurrent outputted by the power supply circuit 10 in the second chargingmode for charging the device to be charged according to the maximumcharging current presently supported by the device to be charged.

The maximum charging current presently supported by the device to becharged may be derived according to the capacity of the battery of thedevice to be charged, a cell system, and the like, or may be a presetvalue.

It should be understood that, the device to be charged may determine thecharging current outputted by the power supply circuit 10 in the secondcharging mode for charging the device to be charged according to themaximum charging current presently supported by the device to be chargedin many ways. For example, the power supply circuit 10 may determine themaximum charging current presently supported by the device to be chargedas the charging current outputted by the power supply circuit 10 in thesecond charging mode for charging the device to be charged, or maydetermine the charging current outputted by the power supply circuit 10in the second charging mode for charging the device to be charged aftercomprehensively considering factors such as the maximum charging currentpresently supported by the device to be charged and its own currentoutput capability.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 to controlthe output of the power supply circuit 10 in the second charging mode asfollows. During charging in the second charging mode, the device to becharged performs the bidirectional communication with the power supplycircuit 10 to adjust the output current of the power supply circuit 10.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 to adjustthe output current of the power supply circuit 10 as follows. The deviceto be charged receives a fourth instruction sent by the power supplycircuit 10, in which the fourth instruction is configured to query apresent voltage of the battery in the device to be charged. The deviceto be charged sends a reply instruction of the fourth instruction to thepower supply circuit 10, in which the reply instruction of the fourthinstruction is configured to indicate the present voltage of thebattery. The power supply circuit 10 adjusts the output current of thepower supply circuit 10 according to the present voltage of the battery.

In some embodiments, the device to be charged may perform thebidirectional communication with the power supply circuit 10 to controlthe output of the power supply circuit 10 in the second charging mode asfollows. The device to be charged performs the bidirectionalcommunication with the power supply circuit 10 to determine whether thecharging interface is in poor contact.

In an embodiment, the device to be charged may perform the bidirectionalcommunication with the power supply circuit 10 to determine whether thecharging interface is in poor contact as follows. The device to becharged receives the fourth instruction sent by the power supply circuit10, in which the fourth instruction is configured to query the presentvoltage of the battery in the device to be charged. The device to becharged sends the reply instruction of the fourth instruction to thepower supply circuit 10, in which the reply instruction of the fourthinstruction is configured to indicate the present voltage of the batteryin the device to be charged. The power supply circuit 10 determineswhether the charging interface is in poor contact according to theoutput voltage of the power supply circuit 10 and the present voltage ofthe battery in the device to be charged. For example, when the powersupply circuit 10 determines a difference between the output voltage ofthe power supply circuit 10 and the present voltage of the battery inthe device to be charged is greater than a predetermined voltagethreshold, it indicates that an impedance obtained by dividing thevoltage difference by the present current value outputted by the powersupply circuit 10 is greater than a preset impedance threshold, and thusit can be determined that the charging interface is in poor contact.

In some embodiments, it can be determined by the device to be chargedwhether the charging interface is in poor contact. For example, thedevice to be charged sends a sixth instruction to the power supplycircuit 10, in which the sixth instruction is configured to query theoutput voltage of the power supply circuit 10. The device to be chargedreceives a reply instruction of the sixth instruction sent by the powersupply circuit 10, in which the reply instruction of the sixthinstruction is configured to indicate the output voltage of the powersupply circuit 10. The device to be charged determines whether thecharging interface is in poor contact according to the output voltage ofthe power supply circuit 10 and the present voltage of the battery inthe device to be charged. After the device to be charged determines thatthe charging interface is in poor contact, the device to be charged maysend a fifth instruction to the power supply circuit 10, in which thefifth instruction is configured to indicate that the charging interfaceis in poor contact. After receiving the fifth instruction, the powersupply circuit 10 may quit the second charging mode.

With reference to FIG. 8, the communication procedure between the powersupply circuit 10 and the device to be charged will be described indetail. It should be noted that, examples in FIG. 8 are merely used tohelp those skilled in the related art to understand embodiments of thepresent disclosure. The embodiments shall not be limited to the specificnumeric values or specific scenes. Apparently, various modifications andequivalents can be made by those skilled in the related art based onexamples in FIG. 8, and those modifications and equivalents shall fallwithin the protection scope of the present disclosure.

As illustrated in FIG. 8, the communication procedure between the powersupply circuit 10 and the device to be charged (or, referred to as thecommunication procedure of the fast charging) may include the followingfive stages.

Stage 1:

After the device to be charged is coupled to the power supply circuit10, the device to be charged may detect a type of the power supplycircuit 10 via the data wires D+ and D−. When detecting that the powersupply circuit 10 is a power supply circuit specifically used forcharging, such as an adapter, the device to be charged may absorbcurrent greater than a predetermined current threshold 12 (which may be,for example, 1A). When the power supply circuit 10 detects that theoutput current of the power supply circuit 10 is greater than or equalto 12 for a predetermined time period (for example, may be a continuoustime period T1), the power supply circuit 10 determines that the deviceto be charged has completed the recognition of the type of the powersupply device. Then, the power supply circuit 10 initiates a negotiationwith the device to be charged, and sends an instruction 1 (correspondingto the above-mentioned first instruction) to the device to be charged toquery whether the device to be charged agrees that the power supplycircuit 10 charges the device to be charged in the second charging mode.

When the power supply circuit 10 receives a reply instruction of theinstruction 1 sent by the device to be charged and the reply instructionof the instruction 1 indicates that the device to be charged disagreesthat the power supply circuit 10 charges the device to be charged in thesecond charging mode, the power supply circuit 10 detects the outputcurrent of the power supply circuit 10 again. When the output current ofthe power supply circuit 10 is still greater than or equal to 12 withina predetermined continuous time period (for example, may be a continuoustime period T1), the power supply circuit 10 sends the instruction 1again to the device to be charged to query whether the device to becharged agrees that the power supply circuit 10 charges the device to becharged in the second charging mode. The power supply circuit 10 repeatsthe above actions in stage 1, until the device to be charged agrees thatthe power supply circuit 10 charges the device to be charged in thesecond charging mode or until the output current of the power supplycircuit 10 is no longer greater than or equal to 12.

After the device to be charged agrees that the power supply circuit 10charges the device to be charged in the second charging mode, thecommunication procedure goes into stage 2

Stage 2:

The power supply circuit 10 sends an instruction 2 (corresponding to theabove-mentioned second instruction) to the device to be charged to querywhether the output voltage of the power supply circuit 10 (the presentoutput voltage) matches the present voltage of the battery in the deviceto be charged.

The device to be charged sends a reply instruction of the instruction 2to the power supply circuit 10, for indicating that the output voltageof the power supply circuit 10 matches the present voltage of thebattery in the device to be charged, or is higher or lower than thepresent voltage of the battery in the device to be charged. When thereply instruction of the instruction 2 indicates that the output voltageof the power supply circuit 10 is higher or lower, the power supplycircuit 10 may adjust the output voltage of the power supply circuit 10to be lower or higher, and sends the instruction 2 to the device to becharged again to query whether the output voltage of the power supplycircuit 10 matches the present voltage of the battery. The above actionsin stage 2 are repeated, until the device to be charged determines thatthe output voltage of the power supply circuit 10 matches the presentvoltage of the battery in the device to be charged. Then, thecommunication procedure goes into stage 3. The output voltage of thepower supply circuit 10 may be adjusted in various ways. For example, aplurality of voltage levels from low to high may be set for the outputvoltage of the power supply circuit 10 in advance. The higher thevoltage level is, the larger the output voltage of the power supplycircuit 10 is. When the reply instruction of the instruction 2 indicatesthat the output voltage of the power supply circuit 10 is higher, thevoltage level of the output voltage of the power supply circuit 10 maybe reduced by one level from the present voltage level. When the replyinstruction of the instruction 2 indicates that the output voltage ofthe power supply circuit 10 is lower, the voltage level of the outputvoltage of the power supply circuit 10 may be increased by one levelfrom the present voltage level.

Stage 3:

The power supply circuit 10 sends an instruction 3 (corresponding to theabove-mentioned third instruction) to the device to be charged to querythe maximum charging current presently supported by the device to becharged. The device to be charged sends a reply instruction of theinstruction 3 to the power supply circuit 10 for indicating the maximumcharging current presently supported by the device to be charged, andthen the communication procedure goes into stage 4.

Stage 4:

The power supply circuit 10 determines the charging current outputted bythe power supply circuit 10 in the second charging mode for charging thedevice to be charged according to the maximum charging current presentlysupported by the device to be charged. Then, the communication proceduregoes into stage 5, i.e., the constant current charging stage.

Stage 5:

When the communication procedure goes into the constant current chargingstage, the power supply circuit 10 may send an instruction 4(corresponding to the above-mentioned fourth instruction) to the deviceto be charged at intervals to query the present voltage of the batteryin the device to be charged. The device to be charged may send a replyinstruction of the instruction 4 to the power supply circuit 10, to feedback the present voltage of the battery. The power supply circuit 10 maydetermine according to the present voltage of the battery whether thecharging interface is in poor contact and whether it is necessary todecrease the output current of the power supply circuit 10. When thepower supply circuit 10 determines that the charging interface is inpoor contact, the power supply circuit 10 may send an instruction 5(corresponding to the above-mentioned fifth instruction) to the deviceto be charged, and the power supply circuit 10 would quit the secondcharging mode, and then the communication procedure is reset and goesinto stage 1 again.

In some embodiments, in stage 2, the time period from when the device tobe charged agrees the power supply circuit 10 to charge the device to becharged in the second charging mode to when the power supply circuit 10adjusts the output voltage of the power supply circuit 10 to a suitablecharging voltage may be controlled in a certain range. If the timeperiod exceeds a predetermined range, the power supply circuit 10 or thedevice to be charged may determine that the communication procedure isabnormal, such that the communication procedure is reset and goes intostage 1.

In some embodiments, in stage 2, when the output voltage of the powersupply circuit 10 is higher than the present voltage of the battery inthe device to be charged by ΔV (ΔV may be set to 200-500 mV), the deviceto be charged may send a reply instruction of the instruction 2 to thepower supply circuit 10, for indicating that the output voltage of thepower supply circuit 10 matches the voltage of the battery in the deviceto be charged.

In some embodiments, in stage 4, the adjusting speed of the outputcurrent of the power supply circuit 10 may be controlled to be in acertain range, thus avoiding an abnormity occurring in the chargingprocess due to the too fast adjusting speed.

In some embodiments, in stage 5, the variation degree of the outputcurrent of the power supply circuit 10 may be controlled to be less thanor equal to 5%.

In some embodiments, in stage 5, the power supply circuit 10 can monitorthe path impedance of a charging loop in real time. In detail, the powersupply circuit 10 can monitor the path impedance of the charging loopaccording to the output voltage of the power supply circuit 10, theoutput current of the power supply circuit 10 and the present voltage ofthe battery fed back by the device to be charged. When the pathimpedance of the charging loop is greater than a sum of the pathimpedance of the device to be charged and the impedance of the chargingwire, it may be considered that the charging interface is in poorcontact, and thus the power supply circuit 10 stops charging the deviceto be charged in the second charging mode.

In some embodiments, after the power supply circuit 10 starts to chargethe device to be charged in the second charging mode, time intervals ofcommunications between the power supply circuit 10 and the device to becharged may be controlled to be in a certain range, thus avoidingabnormity in the communication procedure due to the too short timeinterval of communications.

In some embodiments, the stop of the charging process (or the stop ofthe charging process that the power supply circuit 10 charges the deviceto be charged in the second charging mode) may be a recoverable stop oran unrecoverable stop.

For example, when it is detected that the battery in the device to becharged is fully charged or the charging interface is poor contact, thecharging process is stopped and the charging communication procedure isreset, and the charging process goes into stage 1 again. Then, thedevice to be charged disagrees that the power supply circuit 10 chargesthe device to be charged in the second charging mode, and thecommunication procedure would not go into stage 2. The stop of thecharging process in such a case may be considered as an unrecoverablestop.

For another example, when an abnormity occurs in the communicationbetween the power supply circuit 10 and the device to be charged, thecharging process is stopped and the charging communication procedure isreset, and the charging process goes into stage 1 again. Afterrequirements for stage 1 are met, the device to be charged agrees thatthe power supply circuit 10 charges the device to be charged in thesecond charging mode to recover the charging process. In this case, thestop of the charging process may be considered as a recoverable stop.

For another example, when the device to be charged detects that anabnormity occurs in the battery, the charging process is stopped and thecharging communication process is reset, and the charging process goesinto stage 1 again. The device to be charged then disagrees that thepower supply circuit 10 charges the device to be charged in the secondcharging mode. When the battery returns to normal and the requirementsfor stage 1 are met, the device to be charged agrees that the powersupply circuit 10 charges the device to be charged in the secondcharging mode. In this case, the stop of fast charging process may beconsidered as a recoverable stop.

Communication actions or operations illustrated in FIG. 8 are merelyexemplary. For example, in stage 1, after the device to be charged iscoupled to the power supply circuit 10, the handshake communicationbetween the device to be charged and the power supply circuit 10 may beinitiated by the device to be charged. In other words, the device to becharged sends an instruction 1 to query the power supply circuit 10whether to operate in the second charging mode. When the device to becharged receives a reply instruction indicating that the power supplycircuit 10 agrees to charge the device to be charged in the secondcharging mode from the power supply circuit 10, the power supply circuit10 starts to charge the battery in the device to be charged in thesecond charging mode.

For another example, after stage 5, there may be a constant voltagecharging stage. In detail, in stage 5, the device to be charged may feedback the present voltage of the battery to the power supply circuit 10.The charging process goes into the constant voltage charging stage fromthe constant current charging stage when the present voltage of thebattery reaches a voltage threshold for constant voltage charging.During the constant voltage charging stage, the charging currentdecreases gradually. When the current reduces to a certain threshold, itindicates that the battery in the device to be charged is fully charged,and the whole charging process is stopped.

Embodiments of the present disclosure further provide a power supplydevice. As illustrated in FIG. 9, the power supply device 900 mayinclude a housing 1000, a circuit board 2000 and a power supply circuit3000. The circuit board 2000 may be enclosed by the housing 1000. Thepower supply circuit 3000 may be positioned on the circuit board 2000.The power supply circuit 3000 may be the power supply circuit 10provided in any embodiment of the present disclosure. The power supplydevice 900 may be a device specifically used for charging, such as anadapter or a power bank, or may be other devices capable of supplyingpower and data services, such as a computer. The power supply circuitand the power supply device provided by embodiments of the presentdisclosure have been described above in detail with reference to FIGS.1-9. A control method of a power supply circuit provided by embodimentsof the present disclosure will be described below in detail withreference to FIG. 10. As illustrated in FIG. 10, the control method mayinclude following blocks.

In block 1010, rectification is performed on input alternating currentto output a first voltage having a periodically changing voltage value.

In block 1020, the first voltage is modulated to generate a secondvoltage.

In block 1030, a third voltage is generated based on the second voltage.

In block 1040, rectification and filtering is performed on the thirdvoltage to generate an output current of the power supply circuit.

In block 1050, a feedback signal is generated when a current value ofthe output current reaches a preset current limit value.

In block 1060, the feedback signal is transmitted in an optoelectroniccoupling manner, such that modulating the first voltage to generate thesecond voltage is performed according to the feedback signal, to limitthe current value of the output current below the current limit value.

In block 1070, a voltage of the alternating current is determined.

In block 1080, when the voltage of the alternating current is of a firsttype, the current limit value is set as a first current value.

In block 1090, when the voltage of the alternating current is of asecond type, the current limit value is set as a second current value.

An amplitude of the voltage of the first type is greater than that ofthe voltage of the second type, and the first current value is greaterthan the second current value.

In some embodiments, the method in FIG. 10 may further includecommunicating with a device to be charged, to adjust an output power ofthe power supply circuit, such that an output voltage and/or the outputcurrent of the power supply circuit matches a charging stage where abattery of the device to be charged is currently.

In some embodiments, the charging state in which the power supplycircuit charges the battery includes at least one of a trickle chargingstage, a constant current charging stage and a constant voltage chargingstage.

In some embodiments, communicating with a device to be charged, toadjust an output power of the power supply circuit, such that the outputvoltage and/or the output current of the power supply circuit matchesthe charging stage where a battery of the device to be charged iscurrently, may include: in the constant voltage charging stage,communicating with the device to be charged, to adjust the output powerof the power supply circuit, such that the output voltage of the powersupply circuit matches a charging voltage corresponding to the constantvoltage charging stage.

In some embodiments, communicating with a device to be charged, toadjust an output power of the power supply circuit, such that the outputvoltage and/or the output current of the power supply circuit matchesthe charging stage where a battery of the device to be charged iscurrently, may include: in the constant current charging stage,communicating with the device to be charged, to adjust the output powerof the power supply circuit, such that the output current of the powersupply circuit matches a charging current corresponding to the constantcurrent charging stage.

With respect to the details of the control method, reference can be madeto the above description regarding the power supply circuit, which willnot be elaborated here for simplicity. Further, blocks may be executedin a different order. For example, blocks 1070-1090 may be executedbefore blocks 1010-1060, or may be executed simultaneously with blocks1010-1060, which is not limited in embodiments of the presentdisclosure.

In above embodiments, it is possible to implement the embodiments fullyor partially by software, hardware, firmware or any other combination.When implemented by software, it is possible to implement theembodiments fully or partially in a form of computer program products.The computer program product includes one or more computer instructions.When the computer program instructions are loaded and executed by thecomputer, procedures or functions according to embodiments of thepresent disclosure are fully or partially generated. The computer may bea general-purpose computer, a special-purpose computer, a computernetwork, or any other programmable device. The computer instructions maybe stored in a computer readable storage medium, or may be transmittedfrom one computer readable storage medium to another computer readablestorage medium. For example, the computer instructions may betransmitted from one website, computer, server or data center to anotherwebsite, computer, server or data center in a wired manner (for example,via coaxial cables, fiber optics, or DSL (digital subscriber line)) orin a wireless manner (for example, via infrared, WiFi or microwave). Thecomputer readable storage medium may be any available medium that areaccessible by the computer, or a data storage device such as a server ora data center integrated with one or more available medium. Theavailable medium may be magnetic medium (for example, floppy disk, harddisk and tape), optical medium (for example, DVD (digital video disc)),or semiconductor medium (for example, SSD (solid state disk)).

Those skilled in the art could be aware that, exemplary units andalgorithm steps described in combination with embodiments disclosedherein may be implemented by electronic hardware, or by a combination ofcomputer software and electronic hardware. Whether these functions areexecuted by hardware or software is dependent on particular use anddesign constraints of the technical solutions. Professionals may adoptdifferent methods for different particular uses to implement describedfunctions, which should not be regarded as going beyond the scope of thepresent disclosure.

In several embodiments provided by the present disclosure, it should beunderstood that, the disclosed system, device and method may beimplemented in other ways. For example, the device embodiments describedabove are merely illustrative. For example, the units are merely dividedaccording to logic functions, and can be divided in other ways in actualimplementation. For example, a plurality of units or components may becombined or may be integrated into another system, or some features maybe ignored or not executed. In addition, the mutual coupling or directcoupling or communication connection illustrated or discussed may be viasome interfaces, or direct coupling or communication connection ofdevices or units may be in an electrical, mechanical, or other form.

Units illustrated as separate components may be or may not be physicallyseparated, and components illustrated as units may be or may not bephysical units, i.e., may be located at a same place, or may bedistributed onto multiple network units. Some or all of the units may beselected to implement the purpose of the solution in an embodimentaccording to actual demands.

Moreover, respective functional units in respective embodiments of thepresent disclosure may be integrated in one processing unit, or therespective units may be separate physical existence, or two or moreunits may be integrated in one unit.

Above description is merely specific implementation of the presentdisclosure. However, the protection scope of the present disclosure isnot limited to this. Any change or substitute that is conceivable bythose skilled in the art should be in the protection scope of thepresent disclosure. Thus, the protection scope of the present disclosureshould be defined as the protection scope of claims.

What is claimed is:
 1. A power supply circuit, comprising: a primaryrectifier unit, configured to perform rectification on input alternatingcurrent to output a first voltage having a periodically changing voltagevalue; a modulation unit, configured to modulate the first voltage togenerate a second voltage; a transformer, configured to generate a thirdvoltage based on the second voltage; a secondary rectifier and filteringunit, configured to perform rectification and filtering on the thirdvoltage to generate an output current of the power supply circuit; acurrent feedback unit; an isolation unit; and a control unit; whereinthe current feedback unit is configured to receive the output current,and to send a feedback signal to the isolation unit when a current valueof the output current reaches a preset current limit value; wherein theisolation unit is configured to transmit the feedback signal to themodulation unit in an optoelectronic coupling manner; wherein themodulation unit is configured to perform modulating the first voltage togenerate the second voltage according to the feedback signal, to limitthe current value of the output current below the current limit value;and wherein the control unit is configured to determine a voltage of thealternating current, to set the current limit value of the currentfeedback unit as a first current value when the voltage of thealternating current is of a first type, and to set the current limitvalue of the current feedback unit as a second current value when thevoltage of the alternating current is of a second type, in which anamplitude of the voltage of the first type is greater than that of thevoltage of the second type, and the first current value is greater thanthe second current value.
 2. The power supply circuit of claim 1,further comprising: a first rectifier unit, configured to receive thethird voltage, and to perform rectification on the third voltage toobtain a fourth voltage; a first filtering unit, configured to receivethe fourth voltage, and to perform filtering on the fourth voltage toobtain a fifth voltage; a voltage signal conversion unit, configured toconvert the fifth voltage to an indication signal for indicating a typeof the voltage of the alternating current, wherein the control unit isconfigured to receive the indication signal, and to determine the typeof the voltage of the alternating current according to the indicationsignal.
 3. The power supply circuit of claim 2, wherein the voltagesignal conversion unit is configured to sample the fifth voltage, inwhich the indication signal is a sampling voltage of the fifth voltage.4. The power supply circuit of claim 2, wherein the voltage signalconversion unit is configured to determine the type of the voltage ofthe alternating current according to the fifth voltage, and to generatethe indication signal according to the determined type of the voltage ofthe alternating current, in which the indication signal is one of a highlevel and a low level, the indication signal is configured to indicatethat the voltage of the alternating current is of the first type whenthe indication signal is the high level and to indicate that the voltageof the alternating current is of the second type when the indicationsignal is the low level, or the indication signal is configured toindicate that the voltage of the alternating current is of the secondtype when the indication signal is the high level and to indicate thatthe voltage of the alternating current is of the first type when theindication signal is the low level.
 5. The power supply circuit of claim4, wherein the voltage signal conversion unit comprises avoltage-stabilizing tube and a triode; the voltage-stabilizing tube isconfigured such that, when the voltage of the alternating current is ofthe first type, both the voltage-stabilizing tube and the triode areswitched on, and a collector of the triode is at a low level, and whenthe voltage of the alternating current is of the second type, both thevoltage-stabilizing tube and the triode are switched off, and thecollector of the triode is at a high level; the indication signal is avoltage signal of the collector of the triode.
 6. The power supplycircuit of claim 1, wherein the control unit is further configured tocommunicate with a device to be charged, to adjust an output power ofthe power supply circuit, such that an output voltage and/or the outputcurrent of the power supply circuit matches a charging stage where abattery of the device to be charged is currently.
 7. The power supplycircuit of claim 6, wherein the charging state in which the power supplycircuit charges the battery comprises at least one of a trickle chargingstage, a constant current charging stage and a constant voltage chargingstage.
 8. The power supply circuit of claim 7, wherein the control unitis configured to: in the constant voltage charging stage, communicatewith the device to be charged, to adjust the output power of the powersupply circuit, such that the output voltage of the power supply circuitmatches a charging voltage corresponding to the constant voltagecharging stage.
 9. The power supply circuit of claim 7, wherein thecontrol unit is configured to: in the constant current charging stage,communicate with the device to be charged, to adjust the output power ofthe power supply circuit, such that the output current of the powersupply circuit matches a charging current corresponding to the constantcurrent charging stage.
 10. A power supply device, comprising a housing,a circuit board and a power supply circuit, wherein: the circuit boardis enclosed by the housing; the power supply circuit is positioned onthe circuit board; and the power supply circuit comprises: a primaryrectifier unit, configured to perform rectification on input alternatingcurrent to output a first voltage having a periodically changing voltagevalue; a modulation unit, configured to modulate the first voltage togenerate a second voltage; a transformer, configured to generate a thirdvoltage based on the second voltage; a secondary rectifier and filteringunit, configured to perform rectification and filtering on the thirdvoltage to generate an output current of the power supply circuit; acurrent feedback unit; an isolation unit; and a control unit; whereinthe current feedback unit is configured to receive the output current,and to send a feedback signal to the isolation unit when a current valueof the output current reaches a preset current limit value; wherein theisolation unit is configured to transmit the feedback signal to themodulation unit in an optoelectronic coupling manner; wherein themodulation unit is configured to perform modulating the first voltage togenerate the second voltage according to the feedback signal, to limitthe current value of the output current below the current limit value;and wherein the control unit is configured to determine a voltage of thealternating current, to set the current limit value of the currentfeedback unit as a first current value when the voltage of thealternating current is of a first type, and to set the current limitvalue of the current feedback unit as a second current value when thevoltage of the alternating current is of a second type, in which anamplitude of the voltage of the first type is greater than that of thevoltage of the second type, and the first current value is greater thanthe second current value.
 11. The power supply device of claim 10,wherein the power supply device is an adapter.
 12. A control method of apower supply circuit, comprising: performing rectification on inputalternating current to output a first voltage having a periodicallychanging voltage value; modulating the first voltage to generate asecond voltage; generating a third voltage based on the second voltage;performing rectification and filtering on the third voltage to generatean output current of the power supply circuit; generating a feedbacksignal when a current value of the output current reaches a presetcurrent limit value; transmitting the feedback signal in anoptoelectronic coupling manner, such that modulating the first voltageto generate the second voltage is performed according to the feedbacksignal, to limit the current value of the output current below thecurrent limit value; determining a voltage of the alternating current;setting the current limit value as a first current value when thevoltage of the alternating current is of a first type; setting thecurrent limit value as a second current value when the voltage of thealternating current is of a second type, in which an amplitude of thevoltage of the first type is greater than that of the voltage of thesecond type, and the first current value is greater than the secondcurrent value.
 13. The control method of claim 12, further comprising:communicating with a device to be charged, to adjust an output power ofthe power supply circuit, such that an output voltage and/or the outputcurrent of the power supply circuit matches a charging stage where abattery of the device to be charged is currently.
 14. The control methodof claim 13, wherein the charging state in which the power supplycircuit charges the battery comprises at least one of a trickle chargingstage, a constant current charging stage and a constant voltage chargingstage.
 15. The control method of claim 14, wherein communicating withthe device to be charged, to adjust the output power of the power supplycircuit, such that the output voltage and/or the output current of thepower supply circuit matches the charging stage where the battery of thedevice to be charged is currently, comprises: in the constant voltagecharging stage, communicating with the device to be charged, to adjustthe output power of the power supply circuit, such that the outputvoltage of the power supply circuit matches a charging voltagecorresponding to the constant voltage charging stage.
 16. The controlmethod of claim 14, wherein communicating with the device to be charged,to adjust the output power of the power supply circuit, such that theoutput voltage and/or the output current of the power supply circuitmatches the charging stage where the battery of the device to be chargedis currently, comprises: in the constant current charging stage,communicating with the device to be charged, to adjust the output powerof the power supply circuit, such that the output current of the powersupply circuit matches a charging current corresponding to the constantcurrent charging stage.
 17. The control method of claim 12, furthercomprising: performing rectification on the third voltage to generate afourth voltage; performing filtering on the fourth voltage to generate afifth voltage; and converting the fifth voltage to an indication signalfor indicating a type of the voltage of the alternating current.
 18. Thecontrol method of claim 17, wherein converting the fifth voltage to theindication signal comprises: sampling the fifth voltage to obtain asampling voltage, in which the indication signal is the samplingvoltage.
 19. The control method of claim 17, wherein converting thefifth voltage to the indication signal comprises: generating a highlevel or a low level according to the fifth voltage, for indicating thetype of the voltage of the alternating current.
 20. The power supplycircuit of claim 1, wherein the current feedback unit comprises: acurrent sampling unit, configured to sample the output current of thepower supply circuit; and an operational amplifier, wherein a positiveinput end of the operational amplifier is coupled to the control unit,and a negative input end of the operational amplifier is coupled to anoutput of the current sampling unit, wherein the control unit isconfigured to adjust the current limit value of the current feedbackunit by adjusting a reference voltage received by the positive input endof the operational amplifier.